Apparatus for purifying and silencing the exhaust gases of a hydrocarbon-fueled engine

ABSTRACT

An apparatus for purifying and silencing the exhaust gases generated by a hydrocarbon fuel and more especially a gasoline or diesel-fueled engine. The apparatus has an outer shell having inlet and outlet ports and an access means for servicing the apparatus. Inside the shell there are three coaxially aligned chambers through which the exhaust gases flow in series from the inlet port to the outlet port. The central chamber is packed with a heavy metal catalyst, for example, a platinum-plated catalyst for purifying the exhaust gases. The apparatus is especially useful on automobiles, buses and trucks which are operated in congested center city areas.

United States Patent Smithson et al.

1451 Jan. 25, 1972 Bolek ..23/288 F Primary Examiner-Morris O. Wolk Assistant Examiner-Barry S. Richman A!t0rney-Paul & Paul [5 7] ABSTRACT An apparatus for purifying and silencing the exhaust gases generated by a hydrocarbon fuel and more especially a gasoline or diesel-fueled engine. The apparatus has an outer shell having inlet and outlet ports and an access means for servicing the apparatus. Inside the shell there are three coaxially aligned chambers through which the exhaust gases flow in series from the inlet port to the outlet port. The central chamber is packed with a heavy metal catalyst, for example, a platinumplated catalyst for purifying the exhaust gases. The apparatus is especially useful on automobiles, buses and trucks which are operated in congested center city areas.

9 Claims, 11 Drawing Figures 154] APPARATUS FOR PURIFYING AND SILENCING THE EXHAUST GASES OF A HYDROCARBON-FUELED ENGINE [72] Inventors: Harold R. Smithson, Westtown; Kenneth P. Strohl, Media, both of Pa.

[73] Assignee: Oxy-Catalyst, Incorporated, West Chester,

[22] Filed: Aug. 24, 1970 [21] App1.No.: 66,233

Related US. Application Data [63] Continuation-in-part of Ser. No. 7,821, Feb. 2, 1970,

abandoned.

[52] US. Cl. ..23/288 F, 23/2 E, 23/288 B [51] Int. Cl. ..B0lj 9/04 [58] Field of Search ..23/288 F, 2 E; 60/29 A [56] References Cited UNITED STATES PATENTS 2,772,147 ll/l956 Bowen et a1. ..23/288 F 3,024,593 3/1962 Houdry ...23/288 F UX 3,041,149 6/1962 Houdry.... ..23/288 F 3,083,084 3/1963 Raymond ..23/288 F 3,088,271 5/1963 Smith ..23/288 F X 3,166,382 1/1965 Purse et al.. ..23/288 F 3,166,895 1/1965 Slayter et al ..23/288 F X PATENTEnJmzsmz 3.637.353

4+,L INVENTORS.

H0 R.Smirhson BY Ke n h P. Strohl ATTORNEYS.

PATENTEDJANZSIQTZ 3,637,353 saw 201' 2 b u u INVENTORS.

9o Harold R. Smithson BY Kenneth P. Strohl F I ll Mv /av ATTORNEYS.

APPARATUS FOR PURIFYING AND SILENCING THE EXHAUST GASES OF A I-IYDROCARBON-FUELED ENGINE CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 7,82l, filed Feb. 2, I970 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is concerned with an apparatus for purifying and silencing the exhaust gases generated by hydrocarbonfueled engines.

2. Description of the Prior Art In recent years, there has been a substantial increase in the severity of air pollution and noise pollution, particularly in crowded metropolitan areas. The adverse effects of air pollution are especially noticeable when low wind conditions prevail and temperature inversions occur since this causes a condition commonly known as smog. The dangers of air pollution are well known and accordingly the general public is now insisting that the level of air pollution be substantially reduced.

Noise pollution, while not as well recognized as a health problem as air pollution is still a substantial pollution problem. The excess amounts of noises generated by automobile, trucks and buses does definitely have adverse effects on the hearing ability of persons who are constantly exposed to these conditions. In addition, the high noise level decreases the efficiency as well as adding to the physical discomfort of persons in the immediate vicinity of the noise emission.

One of the major contributors to air and noise pollution in center city areas is the exhaust gases from vehicles such as cars, trucks and buses. Considerable research work has been conducted on apparatus to reduce the level of pollution emitted from vehicles with at best only marginal success. The requirements for the pollution control apparatus are rather stringent. The apparatus must be relatively small, preferably about the size of a conventional acoustic muffler. In addition, the apparatus has to be sufficiently economical, efiicient and long lasting to warrant incorporation on millions of vehicles.

It is relatively simple to reduce air pollution by providing afterburners to completely oxidize the initial reaction products into innocuous byproducts. This, however requires the use of additional fuel and apparatus for which there is no corresponding increase in power output of the engine and therefore a substantial cost in the increase in the cost of the operation of the vehicle. Furthermore, the use of the afterburners further adds to the already acute noise pollution problem.

Another solution has been to catalytically oxidize the byproducts of combustion. However, the devices heretofore suggested have proven to be quite expensive and have required replacement at frequent intervals. The apparatus that was heretofore suggested also did not have any substantial effect on the noise level so that a conventional acoustic muffler was also required.

One type of vehicle which has caused considerable problems with regard to the control of air pollution is the type having diesel fueled engines. These vehicles are generally commercial vehicles such as buses and large trucks. The diesel engines are used in these applications because of the relatively low fuel costs. However, the exhaust gases generated by the diesel engines contain a very high level of pollutants. The high level of pollutants is quite evident from even a cursory examination of these vehicles in operation. The smoking diesel engine is well known to city dwellers as is the very characteristic and nauseating diesel exhaust stench. The problem of controlling pollution of diesel engines is especially acute in congested center city areas since the stop-and-go type driving encountered in these areas causes an even greater level in the emission of pollution.

The problem of reducing the pollution level of diesel engines is especially difficult because of the economic factors involved. As noted above, diesel engines are used almost exclusively on commercial vehicles because of substantial cost savings which are incurred in using diesel fuel. Accordingly, the cost involved in pollution control becomes a critical factor. The cost for pollution control, both direct and indirect, must be relatively low in order to be acceptable to most operators of commercial vehicles. The initial cost of the apparatus must be reasonable and it must be capable of being simply installed on existing vehicles without any substantial modification of the vehicles. In addition, the cost of servicing the apparatus and the time required for servicing must also be relatively low. An indirect cost factor which is especially important is the effect of the pollution control apparatus on fuel consumption. The apparatus must not significantly increase the amount of back pressure of the exhaust gas over that encountered with the original equipment acoustic type muffler in that this increases the fuel consumption considerably.

All of the apparatuses which have been suggested in the prior art were either too expensive to purchase, too costly to maintain or did not significantly lower the emission of engine pollution and noise. In addition, the typical type of apparatus suggested in the prior art either did not significantly lower the level pollution or so increased the back pressure of the exhaust gases that it significantly increased the fuel consumption of the engine.

The problems encountered with gasoline-fueled engines are substantially the same as those encountered with the dieselfueled engines. The pollution problems created by gasolinefueled engines are of a much larger scale because of the greater number of gasoline-fueled vehicles on the road than diesel-fueled vehicles. With regard to the gasoline-fueled commercial vehicles, the same factors with regard to both direct and indirect cost are the primary factors to be considered by the owner of these vehicles with regard to installation of the pollution-controlled devices. With regard to privately owned noncommercial vehicles, it is believed if the cost for the initial installation and the maintenance of the device is not substantial that the public will purchase and utilize pollution control devices in order to improve the quality of the environment. A very distinct problem encountered with the gasoline-fueled vehicle is that gasolines are generally modified with numerous additives and in particular tetraethyl lead which in itself adds pollutants to the air.

It should be further appreciated that there is a class of vehicles which are often operated in relatively closed areas such as warehouses and the like, for example fork lift trucks, in which the exhaust gas must be purified in order to maintain the air in these closed areas in a safe condition for the operators of the vehicles. Most of these trucks run on LPG or other similar fuels which inherently result in a somewhat lower output of pollution. A very distinct problem however is the amount of noise admitted by these devices because they are generally operated in closed areas.

It is accordingly an object of this invention to overcome the aforementioned problems and disadvantages encountered with the prior art pollution control devices.

It is a still further object of this invention to provide an apparatus for purifying and silencing the exhaust gases from a hydrocarbon-fueled engine.

It is a still further object of this invention to provide an apparatus for purifying and silencing the exhaust gases from diesel or gasoline-fueled engines which can be readily installed on existing vehicles, can be simply serviced, and which does not significantly increase the fuel consumption.

Other objects and advantages of this invention will become further apparent hereinafter from a review of the attached drawings and a further reading of the specification and subjoined claims.

The objects of this invention have been achieved by providing an apparatus having an outer shell with inlet and outlet ports and a removable access plate. Positioned within the shell, there are three coaxially aligned chambers. The exhaust gases are introduced into the apparatus through the inlet port and enter the center most chamber. The gases then pass through the apertures in the wall into an intermediate chamber which is packed with a granular heavy metal catalyst which catalytically removes the gaseous impurities from the exhaust gases and silences the noise emitted by the engine. The gases pass from the intermediate chamber to the outer most chamber and exit from the apparatus through the outlet port. The access plate covers an aperture which is in communication with the interior of the central chamber. The access plate is periodically removed and the apparatus is serviced in a simple and efficient manner in order to regenerate the catalytic activity of the catalysts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an illustration of an end view of a preferred embodiment of the apparatus of this invention.

FIG. 2 is a cross-sectional illustration of the apparatus of this invention taken as shown by the lines and arrows 2-2 of FIG. 1.

FIG. 3 is a cross-sectional illustration of the apparatus of FIG. 1 taken as shown by the lines in arrows 3-3 of FIG. 2.

FIG. 4 is an end view of the apparatus of FIG. 1 taken as indicated by the lines and arrows 4-4 of FIG. 2.

FIG. 5 is an enlarged view of the partition wall of the apparatus of FIG. 1 taken at the area identified with the dotted outline on FIG. 2.

FIG. 6 is an alternate embodiment of a type of partition wall which can be employed in the apparatus of this invention.

FIG. 7 is yet an additional alternate embodiment of a type of partition wall which may be advantageously utilized in the apparatus of this invention.

FIG. 8 is a cross-sectional enlargement of the partition wall of FIG. 7 taken as indicated by the lines and arrows 8-8 of FIG. 7.

FIG. 9 is an alternate embodiment of the apparatus of this invention having an offset straight through flow pattern.

FIG. 10 is yet an additional alternate embodiment of this invention having a straight through flow pattern.

FIG. 11 is an illustration of an alternate embodiment of the apparatus of this invention having a right-angle inlet port and a vertical outlet port.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of this invention is utilized on cars, buses, trucks, industrial vehicles and the like to purify and silence the exhaust gases emitted by the engines of these vehicles. The apparatus is useful on vehicles which are run on hydrocarbon fuels. The hydrocarbon fuels can for example, be gasoline, diesel oil, kerosene, LPG or the like. Ideally, the fuel should be capable, on combustion in the engine, of burning completely to carbon dioxide and water. However, the exhaust gases of internal combustion engines usually consist of many different types of products such as unburned hydrocarbons, carbon monoxide, and numerous pollutants produced as a result of incomplete combustion or because of natural or additional materials added to the hydrocarbon fuels. The apparatus of this invention is preferably employed for the purpose of purifying the exhaust from engines employing relatively pure hydrocarbon fuels. The invention commercially is best utilized with diesel oil, gaseous hydrocarbons such as LPG and unleaded gasolines. Hydrocarbon products modified with additives, such as tetraethyl lead and the like which are commonly added to high test gas in order to raise the octane, can also be purified in the apparatus of this invention. However, it should be appreciated that these additives, especially tetraethyllead,

tend to coat the catalyst and deactivate the catalytic activity rather rapidly in comparison to unleaded gasolincs.

The various types of apparatuses of this invention which are illustrated in the drawings are adapted to be connected to the exhaust pipe of a car, bus or truck, in place of the conventional original equipment acoustic muffler supplied as part of the original equipment. The preferred apparatus 10 has an outer shell 12. There are inlet ports l4, l6 and an outlet port 18 at one terminal end 20 of the apparatus. At the opposite terminal end 22 there is a removable access plate 24 which is secured to the end 22 by means of bolts 26.

There are three chambers, a central chamber 30, an intermediate chamber 32 and an outer chamber 34 aligned coaxially within the shell 12. The chambers 30, 32, 34 are separated from each other by perforated partition walls 36, 38. The intermediate chamber 32 is packed with a granular heavy metal catalyst material 40. The exhaust gases from the engine enter the apparatus 10 through the inlets l4, l6 and pass into the central chamber 30. The gases then pass the apertures in the partition wall 36 into the intermediate chamber 32 wherein the gases come in contact with the heavy metal catalyst 40 which catalytically purifies and silences the exhaust gases. The gases then pass through the apertures and the partition wall 38 into the chamber 34 and exit from the apparatus to the outlet port 18. It is to be understood that the various elements of the apparatus 10 are secured together, as for example by welding or bracing, unless otherwise specifically noted.

All of the structural parts of the apparatus 10 are made preferably of a heat resistant, corrosion resistant material. The preferred material for forming the apparatus 10 is high chromium stainless steel. The extra initial cost involved in using stainless steel is justified by the considerably longer useful life of the apparatus 10 when prepared in stainless steel.

The outer shell 12, as illustrated, is of a cylindrical configuration. The outer shell could also be oval or rectangular in shape if desired. The exact dimensions of the outer shell are to some extent determined by the space available in the vehicle on which it is to be installed and the cubic inch displacement of the hydrocarbon fueled engine. The controlling factors in determining the overall dimensions of the apparatus 10 is the total surface area and total volume in each of the chambers 30, 32, 34. The surface areas and volumes can be increased by either increasing the diameter or the length of the apparatus [0 or by a combination of both. As with a conventional acoustic muffler, an engine with a larger cubic inch displacement requires the use of a larger purifier and silencer 10. With existing vehicles, it has been found that satisfactory results can be obtained by replacing the original equipment acoustic muffler with the apparatus 10 of this invention which has approximately the same general exterior configuration. With newly designed vehicles, the exterior configuration can, of course, be modified within reason to be accommodated in the space availablev The apparatus 10 should be so installed on the vehicle so that the access plate 24 will be readily available to servicemen for reasons which will be pointed out below.

The inlet ports l4, l6 and the outlet port 18 are at one end of the apparatus. The apparatus 10, as illustrated, has dual inlet ports l4, 16 since it is intended for use on a vehicle having a dual exhaust system. If the intended vehicle had only a single exhaust, only a single inlet would be required. The diameters of the inlet ports 14, 16 and the outlet port 18 are related to each other so that there would be no measurable increase in the restriction to the flow of the gases through the apparatus as compared to an acoustic muffler. In the apparatus 10, as illustrated in FIGS. 14, there are two inlet ports l4, l6 and a single outlet port 18, all of approximately the same diameter.

The exhaust gases from inlet ports l4, 16 enter the central chamber 30. Chamber 30 extends approximately the entire length of the apparatus 10 except for the section at one end 20 wherein the outer chamber 34 passes about the end of the apparatus 10. The chamber 30 is surrounded by a partition wall 36 is perforated so as to provide apertures 44 for the exhaust gases to flow through. The apertures 44 may be of any particular shape such as rectangular slots as shown, or may be circular 44. square, triangular 44", etc. One advantage of the triangular slots 44 shown in FIG. 7 is that the punched out sections shown in FIG. 8 tend to both guide the exhaust gases in a direction normal to the flow through the catalyst bed and also prevent, to some extent, shifting of the catalyst in the intermediate chamber. The inner surfaces of the partition wall 36 should be relatively smooth. If the apertures 44 are punched through the wall 36, they should advantageously be punched so that any rough edges do not project inwardly. The smooth inner surface of the partition wall 36 is required in order to limit as much as possible the reduction in the velocity or pres sure of the exhaust gases as they pass through the apparatus 10.

The apertures 44, 44', 44" should be relatively small. The dimensions of the apertures is important in that the partition wall 36 retains the catalyst 40 in the intermediate chamber 32. Accordingly, the dimensions of the apertures 44 must be selected so as to prevent the escape of the catalyst 40 from the intermediate chamber. With the catalysts most suitable for use in the apparatus 10 of this invention, the apertures should be such that a Vsto 3/ 16-inch particle depending on the particular size catalyst employed, will not pass through the apertures 44 in the partition 36.

A very important factor with regard to the pressure drop through the apparatus 10 is the relative amount of open spaces in the partition wall 36. If there are insufficient openings in the partition wall 36, there will be a very large and undesirable pressure drop through the apparatus 10, which as noted above, causes an increase in the fuel consumption of the engine in order to obtain a given amount of usable power. A certain amount of pressure drop will occur in any muffler or purifier. It has been found that good results are obtained when about 30 to 40 percent of the surface area of the partition wall is removed to provide the apertures 44. However, in order to insure that the apparatus 10 will operate properly and still have back pressure characteristics no greater than the back pressures encountered with the standard original equipment mufflers, the openings should be limited from 33 to 36 percent with an optimum result being obtained when about 35 percent of the surface area of the partition wall is removed to provide the apertures 44.

The intermediate chamber 32 is coaxially aligned about the central chamber 30. The inner partition wall 36 forms the inner wall of this chamber with the outer partition wall 38 forming the outer wall of the chamber 32. The outer partition wall advantageously has approximately the same configuration as that described above for the inner partition wall 36. At the second terminal end of the .apparatus, there is provided a fill plug 46 which is used for inserting large amounts of the catalyst 40 into the chamber 32. There is a reservoir 48 which is positioned vertically above the chamber 32. The reservoir 48 extends through the outer shell I2 and the outer chamber 34. A cap 50 is secured to the upper portion of the reservoir. The reservoir 48 is filled with catalyst 40. The function of this reservoir is to assure that the chamber 32 is uniformly filled with the catalyst 40 at all times. When the catalyst 40 is initially inserted into the chamber 32 through the filling plug 46 and the vehicle is thereafter used, the catalyst 40 will tend to settle due to vibrations. This settlement would normally cause the layer of catalysts to be thinned out at the upper portion of the chamber 32 and the effectiveness of the apparatus 10 would be considerably reduced. However, by providing the reservoir 48, any loss of volume of the catalyst 40 is compensated by tlie gravity feed of excess catalyst 40 from the reservoir 48 into the upper portion of the chamber 32. In addition, this reservoir may also be used for periodically adding relatively small amounts of the catalyst 40 to the chamber 32 to compensate for any slight losses encountered during use of the apparatus.

The outer most chamber 34 is coaxially aligned about the immediate chamber 32 and the central chamber 30. The outer partition wall 38 forms the inner wall and the shell 12 forms the outer wall of the outer chamber 34. The outer chamber 34 has an end section 52 which extends over the terminal end 20 of the apparatus I0. This section 52 assists in removal of exhaust gases from the chamber 34 and acts as a sound insulating and strengthening member for the forward end 20 of the apparatus l0. The exhaust gases pass from the intermediate chamber 20 into the outer chamber 34 through apertures in the outer partition wall 38. The gases then exit from the outer chamber 34 through the outlet port 18.

The catalyst which is employed in the apparatus of this invention may be selected from various well-known types of oxidation catalysts. The preferred class of catalysts are the heavy metal catalysts and, in particular, the heavy metal catalysts which are coated on support mediums. The heavy metals which may advantageously be used in this invention are for example, copper, copper alloys such as the copper-chromium alloys, palladium, cobalt, zinc, gold or platinum. The preferred heavy metal catalysts from both a performance standpoint and especially with regard to longer term usage are the platinum metal catalysts. The platinum metal is preferably coated on a heat-resistant support medium such as aluminum oxide or a ceramic material. The catalyst is prepared in the form of metal coated granules. There is a fairly wide range of particle sizes which may be satisfactorily used in the apparatus of this invention with catalysts having an average diameter of approximately three-sixte enths of an inch having been found to be most effective. I

The depth of the catalyst 40 in the chamber 32 has a definite effect on the degree of impurities removed from the exhaust gases. The thicker the bed of the catalyst, the more effective is the degree of the removal of impurities from the exhaust gases. However, the thicker the catalyst bed, the greater is the back pressure developed as the exhaust gases pass through the chamber 32. In addition, the more tightly packed the catalyst, the greater will be the back pressure developed. It

' has been found, however, the optimum results are obtained and in fact the original specified back pressure can often be reduced using a 3/1 o-inch-diameter catalyst and lVzto 2-inch catalyst bed. It should be appreciated, however, that the catalyst size can be varied as well as the thickness of the catalyst bed and still obtain a satisfactory degree of removal of impurities from the exhaust gases and reduce in noise level.

The apparatus of this invention is highly effective in removing both gaseous and solid impurities, for example, carbon and the like from exhaust gases. Depending upon the working condition of the engine and the driving conditions under which the vehicle is operated, solid impurities, especially carbon will accumulate in the apparatus primarily in the central chamber and the areas immediately adjacent the central chamber wherein the catalyst is packed. The accumulation of the particulate material in this area decreases the efficiency of the apparatus.

A primary advantage of the apparatus of this invention is that it can be readily serviced to remove the accumulation of impurities from the central chamber 30 and thereby regenerate the catalytic activity of the catalyst in the apparatus 10. The access plate 24 is removed by releasing the bolts 26 which hold it to the bolt circle 54. The access plate 24 covers an aperture 56 in the end wall 22 which is in direct communication with the interior of the central chamber 30. An accumulation of loose material in this chamber 30 can readily be removed by such simple expediences as vacuuming it out. It has been found that the simplest and most efficient method of servicing the apparatus is simply to burn out the accumulated materials from the apparatus. A burner is mounted onto the same bolt circle 54 to which the access has previously secured. The burner is ignited and maintained at a temperature sufficient that the carbon accumulation in the central chamber and the immediately adjacent areas is burned to carbon dioxide and exhausted through the outlet ports 18. The high heat generated by the burner also tends to decompose the other impurities which are deposited on the catalyst and these also escape from the apparatus through the outlet port. The servicing of the apparatus is simple and does not require the use of a skilled mechanic to conduct the servicing. It should be further noted that even if the burner is left on an excessive length of time after the carbon impurities have been burned off, this will not injure the components of the apparatus of this invention. The removal of the impurities from the surface of the catalyst regenerates the catalytic activity of the catalyst. The servicing of the apparatus can be done in a relatively short time during normal servicing of the vehicle and does not require the removal of the apparatus from the vehicle. Since no parts of the apparatus then have to be regularly replaced in routine service, the service costs of the apparatus are relatively low.

It is considerably more important however, to note that the apparatus of this invention when properly serviced and maintained will significantLyreduce the air pollution generated by hydrocarbon fuel diesel engine, especially gasoline and dieselfueled engines. Using the apparatus of this invention even on vehicles having a relatively high degree of pollutant emission, the impurities in the exhaust gas can be reduced to a level wherein the exhaust does not have any significant amount of particulant material in it, has a low amount of carbon monoxide and does not have a noticeable odor.

The operation of the apparatus 10 may be best understood by reference to FIG. 1 with regard to the flow of the exhaust gases as it passes from the'exhaust ports l4, 16 to the outlet port 18. The exhaust gases enter the apparatus 10 in a series of small volumes as each cylinder of the engine is exhausted. The gas, as it enters the inlet ports l4, 16, is highly compressed and hot. When this gas enters the central chamber 30 it expands. Because of the expansion of the gases, a considerable amount of solid material in the gas precipitates out and deposits in the central chamber. The expanded, somewhat cooled gas, then enters the intermediate chamber 32 through the apertures 44 in the partition wall. The packed particles of the catalyst 40 diffuses the gas thereby substantially reducing the noise level of the exhaust gases. The heavy metal catalyst, which as noted above may be a copper chromium alloy, palladium, cobalt, zinc, gold or most preferably platinum catalyst, converts the undesirable byproducts of the combustion into harmless gases. This is done primarily by an exothermic oxidation reaction. The carbon monoxide in the gases catalytically oxidizes to carbon dioxide. The residual hydrocarbons in the exhaust are catalytically oxidized to carbon dioxide and water. Other undesirable products such as formaldehyde and the like are also substantially reduced to inert products. When the apparatus of this invention is employed and is properly serviced, the percent of poisonous gases in the exhaust for example, carbon monoxide, hydrocarbons. formaldehyde. acrylon, etc., can be reduced by at least 90 percent and this is accomplished without any substantial increase in the back pressure characteristics as compared with the standard original equipment type acoustic mufflers.

The present invention has thus been described by specific reference to the embodiment illustrated in FIGS. 1 to 4. It should be appreciated however, that the present invention is not limited to this specific type of configuration. Depending upon the particular requirements of the vehicle upon which the apparatus is to be installed, the position and angle of entry of the inlet port and outlet port and the exact location of the access plate can be varied as required to permit installation on the vehicle.

In FIG. 9, an alternate type of apparatus 58 is illustrated wherein the inlet port 60 is at one end of the apparatus while the outlet port 62 is at the opposite end of the apparatus in an offset position from the center of the apparatus. The access plate 64 is positioned at the outlet end of the apparatus 58. A reservoir fill tube 67 and end fill plugs 66 are provided as in the first embodiment.

A still additional embodiment 68 is provided as shown in FIG. 10. In this embodiment, there is an actual axial alignment of the inlet and the outlet ports. It should be noted however,

that the exhaust gases must pass through each of the chambers, more particularly the catalyst packed intermediate chamber, because of the end plate 76 which effectively separates the chambers to prevent a direct flow through the apparatus 68. The access means and the inlet port 70 in this particular embodiment are an integral unit. The inlet port is bolted to the apparatus 68 and is removed by removing the bolts which provide access to the interior of the apparatus 68. The usual reservoir 77 and the fill plugs 78 are provided in this embodiment.

An additional embodiment of this invention is disclosed in FIG. 11. The exhaust gases enter the apparatus 80 through the inlet port 82 which is at right angles to the chambers of the apparatus and the gases flow outwardly through the exhaust outlet 84. The end plate 86 prevents direct flow through the apparatus with all of the exhaust gases passing through the catalytic chamber 88. The access port is provided at the base of the apparatus 90. The usual catalytic reservoir and fill plugs are also supplied in this embodiment (not shown).

It should be appreciated that the embodiments shown above are typical embodiments and that other variations are possible without departing from the spirit or scope of this invention. For example, more than one catalytic chamber could be pro vided in order to limit the degree of purification in any one zone or to extend the working time possible between servicing of the apparatuses. It is also possible to use a series of the apparatuses of this invention or to include a baffle means or the like within the apparatuses in order to further direct the flow of the gases through the apparatus.

The exact frequency of servicing required as noted above will vary depending upon the operating efficiency of the motor of the vehicle and the type of driving conditions under which the vehicle is operated. With a properly sized apparatus, servicing should not be required more than once or twice a year. Higher mileage commercial vehicles will of course require more frequent servicing in order to maintain the antipollution effect of the apparatus of this invention. The best test to determine the efficiency of the apparatus of this invention is to analyze the exhaust gases to determine the content of the gases. Apparatus is commercially available for this particular purpose. This gives an exact reading of the amount of reduction in the pollution level obtained upon treatment with the apparatus of this invention.

In order to further illustrate the present invention, the following examples are given by way of illustration. The following examples are not intended to limit in any way the scope of the invention beyond that of the subjoined claims. All parts are given in parts by weight, unless otherwise indicated.

EXAMPLE I In order to evaluate the effectiveness of the apparatus of the present invention, the apparatus of this invention was on a diesel bus which was used for commuter transportation in a metropolitan area. The bus that was obtained for this test had the original equipment acoustic muffler. The bus was a relatively late model bus, but the exhaust had a characteristic black color exhaust on startup and a very strong diesel stench. In order to obtain the degree of pollution emitted by the bus, the bus was driven on a center city commuter loop and the exhaust gases were monitored. It was found during this test, that the pollution level of the buss exhaust averaged about 1,000 thousand parts per million. The exhaust muffler of the bus was replaced with an apparatus prepared in accordance with the present invention. The apparatus was prepared in substantial compliance with the description given in the FIGS. 1-5. The muffler was approximately 22 inches in length and I6 inches in diameter. The central chamber had an outside diameter of about 10 inches, while the intermediate chamber had an outside diameter of approximately 14 inches. The catalyst employed was a 3/ 16-inch platinum metal coated aluminum oxide catalyst and the bed was approximately 2 inches thick. The interior partition wall 36 was punctured with slots three thirty-seconds of an inch by one-half inch in length. The open area of the partition wall comprised approximately 35 percent of the interior surface of the inner partition. The bus was again operated on the same commuter loop under the same driving conditions. The pollution level of the exhaust gas was again monitored and was found that the exhaust level had been reduced from l,000 parts per million to parts per million. Furthermore, the exhaust, when subjectively examined, was found to be substantially colorless and did not have the characteristic diesel stench. The back pressure characteristics of the apparatus of the present invention was compared with the back pressure characteristics of the standard original equipment acoustic muffler and it was found that there was no sidered to be clearly justified by the minimal amount of cost involved.

EXAMPLE 2 A pair of GM buses of exactly the same model and age with approximately the same mileage were tuned up so as to be running at the manufacturers recommended specifications. Each bus was evaluated with its original equipment muffler and the noise emission at various r.p.m.s was found to be for all intents and purposes identical with regard to noise level.

One of the buses, Ser. No. 4,307, was left in its original condition. The second bus, Ser. No. 4,305, was left in its original condition with the exception that the original equipment muffler was replaced with the apparatus of this invention as described in example 1.

The noise level was evaluated as follows. The buses were parked exhaust outlet to exhaust outlet approximately 68 feet apart. The exhaust outlets were about inches above the ground. A microphone was placed 45 inches above the ground approximately 1 meter from the exhaust pipes of each bus. The engines were then run without the conventional rear cover so as to prevent diffusion of the engine noises. The engines were run at various r.p.m.s but without applying a load because of the particular test conditions employed. The test were conducted in a closed building to prevent any distortion of the sound effects to wind changes and other similar factors.

Readings were taken on the dbA scale and also for octave bands from 3l.58,000 Hertz (c.p.s.). The octave bands db. levels were converted to sones which permitted direct comparison of the noise levels between buses equipped with the conventional original equipment mufflers and the mufflers of this invention. The comparisons are shown below in table I.

4307 at 2,100 rpm.

Nora-(LE. Original Equipment; I=Apparntus of InVcntiOn.

EXAMPLE 3 A Clark forklift truck having about a 300 CID 4 cylinder engine was tuned to manufacturers specifications. The engine was propane fueled. The original equipment muffler was replaced with a brand new original equipment muffler. The engine was started and allowed to warm up to normal operating conditions and the exhaust gases were then evaluated at a low idle, fast idle and operating a full load at 5 miles an hour. The test vehicle was then run under normal operating conditions for approximately 2,000 hours and reevaluated.

The same test vehicle was reevaluated with the exception that the original equipment muffler was replaced with an apparatus of approximately the same exterior dimensions of a type similar to that shown in FIG. 9.

The test showed that both using the conventional muffler and the muffler of the present invention that there was a higher level of pollution emission per pound of fuel consumed at the idle than at the medium speed with a load, that is at 5 miles per hour. The apparatus of this invention, when installed, substantially reduced the pollution level by an amount of about percent of that encountered with the conventional original equipment muffler. After approximately 5,000 hours of operation under normal driving conditions, there was a noticeable drop in the efficiency of the removal of the pollutants to about 4060 percent of that originally encountered with the apparatus of this invention.

The mufiler was removed from the vehicle and the access plate was taken off. A diesel fueled burner was mounted onto the bolt circle of the apparatus and ignited. The heat generated by the burner consumed the carbon and other impurities in the muffler. The muffler was then reinstalled and reevaluated. It was found that the apparatus after having been burned off had substantially the same efficiency, that is approximately 90 percent removal of impurities as that initially obtained with the virgin catalytic material.

With regard to the other operating conditions of the vehicle, it should be noted that the fuel consumption was carefully monitored and it was found that the fuel consumption was slightly better with the experimental apparatus of this invention. This indicates that the muffler of this invention creates less back pressure on the engine than the original equipment muffler supplies with the vehicle. The noise level was subjectively determined and found to be at least as quiet as that obtained with the original equipment muffler.

The forklift truck was converted to run on lead-free gasoline. Equivalent results were obtained as when propane was used as the fuel. The useful life of the catalyst would have been substantially reduced, however, if leaded gasoline was used in place of either propane or unleaded gasoline.

It should be fully appreciated that the above examples are given by way of illustration of the present invention and are not intended to limit in any way the scope of the subjoined claims.

What is claimed is:

1. An apparatus for purifying and silencing the exhaust gases of a hydrocarbon-fueled engine, said apparatus comprising in combination; a closed tubular shell member having an inlet port, an outlet port, and a removable access means, said shell member further having partition means within said shell member dividing the interior of the shell into a central chamber, an intermediate chamber and an outer chamber, said chambers being coaxially aligned with each other and said shell member; said inlet port being in communication with the central chamber and said outlet port being in communication with the outer chamber; 30-40 percent by area of said partition means being removed by perforation of said partition means to provide apertures whereby the exhaust gases enter ing the inlet port flow in series through the central, intermediate and outer chambers and out the outlet port, said intermediate chamber being packed with an effective amount of a granular heavy metal catalyst sufficient to purify a major proportion of the exhaust gases generated by said engine and said removable access means covering an aperture in communication with said central chamber whereby when said access plate is removed, the apparatus can be serviced so as to regenerate the catalysts in the intermediate chamber.

2. The apparatus according to claim 1 wherein about 35 percent of said partition means between the central chamber and intermediate chamber is perforated to provide said apertures.

3. The apparatus according to claim I is a heavy metal oxidation catalysL.

4. The apparatus according to claim 1 is platinum.

5. The apparatus according to claim 1 wherein said catalyst is metallic platinum supported on a heat resistant support material.

6. The apparatus according to claim 1 wherein said catalystwherein said catalyst wherein said catalyst has a diameter of about three-sixteenths of an inch.

7. The apparatus according to claim I wherein the inter-. mediate chamber is in communication with a reservoir means for holding excess amounts of said catalyst whereby the amount of catalyst in said intermediate chamber is maintained at a constant level. 

2. The apparatus according to claim 1 wherein about 35 percent of said partition means between the central chamber and intermediate chamber is perforated to provide said apertures.
 3. The apparatus according to claim 1 wherein said catalyst is a heavy metal oxidation catalyst.
 4. The apparatus according to claim 1 wherein said catalyst is platinum.
 5. The apparatus according to claim 1 wherein said catalyst is metallic platinum supported on a heat resistant support material.
 6. The apparatus according to claim 1 wherein said catalyst has a diameter of about three-sixteenths of an inch.
 7. The apparatus according to claim 1 wherein the intermediate chamber is in communication with a reservoir means for holding excess amounts of said catalyst whereby the amount of catalyst in said intermediate chamber is maintained at a constant level.
 8. The apparatus according to claim 1 wherein about 33-36 percent of said partition means between the central chamber and said intermediate chamber is perforated to provide said apertures.
 9. The apparatus according to claim 8 wherein said apertures are of a size suffiCient to retain said granular catalyst having a diameter from 1/8 to three-sixteenths of an inch in said intermediate chamber. 